Oops, I did misunderstand. I think this is what you wanted:
|---+------+-------+-------+-------+-------+---|
| ! | Jahr | Menge | Preis | BIPn | BIPr | W |
|---+------+-------+-------+-------+-------+---|
| # | 1 | 10 | 2.8 | 28.00 | 0 | |
| # | 2 | 12 | 0.7 | 8.40 | 33.60 | |
| # | 3 | 4 | 4.00 | 16.00 | 2.80 | |
|---+------+-------+-------+-------+-------+---|
| _ | | | | suma | sumb | |
| | | | | 52.40 | 36.4 | |
#+TBLFM: address@hidden;%.2f::@2$6=0::$sumb=vsum(@address@hidden)
Here I add a formula to set the first row to 0.